Piston and cylinder apparatus arranged for cleaning

ABSTRACT

The cylinder has at least one opening on each side of the piston, these openings serving as inlet and outlet for a liquid; and at each end position of the piston, the cylinder has an annular zone in which the internal diameter of the cylinder along a substantial part of its periphery is larger than the diameter of annular seals on opposite ends of the piston. These annular zones of the cylinder communicate with respective cylinder openings and are located so that when the piston is in either end position, the piston seal nearest the corresponding cylinder end is opposite the corresponding zone while the other piston seal is in sealing engagement with the inside of the cylinder, whereby the seals can be effectively flushed with cleaning liquid without disassembling the piston-cylinder combination.

United States Patent Johansson July 1, 1975 54] PISTON AND CYLINDER APPARATUS 2,899,248 8/1959 Mercier 92/82 x R LE N] 2,902,007 9/1959 Rockwell ...91/401x ARRANGED F0 e A No 3,004,524 10/1961 McCay et al. 1. 91/401 x [75] Inventor: Bjorn-Glow Johansson, Lomma,

Sweden Primary Examiner-Martin P. Schwadron [73] Assignee: Alia-Laval AB, Tumba, Sweden Assistant ExaminerAbraham Hershkovitz Filed: June I973 Attorney, Agent, or Firm-Cyrus S. Hapgood {21 Appl. No.: 369,303 [57] ABSTRACT The cylinder has at least one opening on each side of Fol-mg Appl'cauon Pnonty Data the piston, these openings serving as inlet and outlet June for a liquid; and at each end position of the piston, the

- cylinder has an annular zone in which the internal di- [52] US. Cl. 91/454; 92/78; 92/80; ameter f h u d along a substantial pan of its 92/82; 92/372 92/169 periphery is larger than the diameter of annular seals [51 Int. Cl. FlSb 11/08; FlSb 13/04 on opposite d f the piston These annular zones of Field of Search 92/781 1 80, 821 87, the cylinder communicate with respective cylinder 92/159- 162 1 162 1 [741 86-5; openings and are located so that when the piston is in 91/400, 60M53 either end position, the piston seal nearest the corresponding cylinder end is opposite the corresponding Reiel'ences Cmd zone while the other piston seal is in sealing engage- UNITED STATES PATENTS ment with the inside of the cylinder, whereby the seals 352,033 11 /I886 St. John 91/454 can be effectively flushed with Cleaning liquid Without 1,294,061 2/1919 Dexter 91/401 X disassembling th pist y nd r m ination. 2.6l6,522 ll/l952 Van Heeckeren et al.....: 92/80 X 2,711,157 6/l955 Halward 92/162 R x 7 Claims, 3 Drawing Flames 22 2O 2'! as m E 4 2 25 t r 23 5 1 2 1 3 4 j I PISTON AND CYLINDER APPARATUS ARRANGED FOR CLEANING The present invention relates to an apparatus com prising a piston adapted to reciprocate in a cylinder between two end positions and having annular sealing means at each of its ends, the cylinder being provided with at least one opening on each side of the piston which serves as inlet and outlet for liquid. The piston may be reciprocated within the cylinder either by a piston rod connected therewith or by means of the liquid which is supplied to the cylinder, by causing the liquid pressure to act alternately on opposite sides of the piston.

Apparatus of this kind are used in different fields, as for measuring liquids (see, for instance, French Pat. No. 1,595,934). Within the food stuff industry they have been used to a relatively limited extent, however, as they are very difficult to clean. it is especially difficult to obtain a satisfactory cleaning of the piston sealing means and the grooves therefor in the piston. Such cleaning has hitherto required removal of the piston from the cylinder.

The principal object of the present invention is to provide an apparatus of this type which can be adequately cleaned without disassembling it.

According to the invention, the inside of the cylinder is provided at each end position of the piston with an annular zone in which the internal diameter of the cylinder along a substantial part of its periphery is greater than the diameter of the piston sealing means. Each of these zones is connected with the respective cylinder opening and is positioned so that when the piston is in either end position, the piston seal nearest the corre sponding cylinder end is located opposite a said zone while the other piston seal is in sealing engagement with the inside of the cylinder.

With this construction, the piston seals will be uncovered, one at a time, when the piston reaches its end positions. This enables an effective cleaning of the seals without impairing the normal functioning of the apparatus, as there will always be one seal in engagement with the inside of the cylinder. Preferably, the cylinder has a annular recess in each of the said zones, so that each of the piston seals will be uncovered around its entire periphery in the corresponding end position of the piston.

The cylinder openings on both sides of the piston are preferably situated in the said annular cylinder recesses. For obtaining a continuous movement of cleaning liquid within the cylinder, the inlets for liquid on both sides of the piston may open tangentially into the cylinder.

As previously indicated, it is possible to obtain a satisfactory cleaning of the new apparatus by letting the piston reciprocate within the cylinder as in the normal manner, the apparatus being passed through by cleaning liquid instead of liquid to be measured. During a cleansing operation of this kind, the cleaning liquid will be supplied to and leave the apparatus intermittently. By the present invention it is also possible, however. to clean the apparatus in another way so that a continuous flow of cleaning liquid may be maintained through the apparatus. In certain cases, this may be a necessary condition for having the apparatus constitute one of several interconnected units in a plant, which is arranged to be cleaned so that one and the same cleaning liquid is forced through all of the units of the plant in a sequence. That is, certain units require a continuous flow of cleaning liquid for obtaining an effective cleaning. The apparatus must then have separate inlets and outlets on both sides of the pistion, which are arranged to be closed and opened by means of suitable valves. Further, the apparatus must have means arranged to operate these valves in such a way that the inlet and the outlet on one side of the piston are kept open, while the inlet and outlet on the other side of the piston are kept closed. On cleaning, the piston may then be maintained in one end position while cleaning liquid is caused to flow through the cylinder by way of the inlet and the outlet in this part of the cylinder, after which the piston may be moved to and be maintained in the other end position while cleaning liquid is caused to flow through the cylinder by way of the inlet and the outlet in the opposite part of the latter. An effective cleaning of the piston seals, which will be uncovered one at a time at the respective end positions, will then be obtained. If required, cleaning of this kind may be combined with cleaning of the first-described kind with the piston reciprocating within the cylinder.

If the apparatus is arranged so that the axis of the cylinder forms an angle with the horizontal plane, there is a risk that gas in the form of small bubbles in the liquid to be measured is accumulated below the piston in the lower part of the cylinder. According to a further feature of the invention for avoiding this, the piston is pro vided with a recess between its two seals, the piston recess and each of the said zones in the cylinder having an axial extension such that the piston recess will come into communication with the difierent zones in the respective end positions of the piston.

The present invention is described in more detail below with reference to the accompanying drawing, in which FIG. 1 is a flow diagram of a system including an apparatus according to the invention, FIG. 2 is a longitudinal sectional view of one form of apparatus according to the invention, and H6. 3 is a cross-sectional view along the line 11] III in FIG. 2

In FIG. 1, a cylinder 1 contains a piston 2 reciprocable therein between two end positions. An inlet conduit 3 opens into the cylinder and an outlet conduit 4 leads from the cylinder at one side of the piston 2, and an inlet conduit 5 opens into the cylinder and an outlet conduit 6 leads from the cylinder at the other side of the piston. The two inlet conduits 3 and 5 start from a common conduit 7, and the two outlet conduits 4 and 6 open into a common conduit 8. ln the inlet and outlet conduits are shut-off valves 9-12 which, via connections 13-16, are connected to a common control unit 17. The conduit 7, common to the inlet conduits, leads from a container 18. A pump 19 in the conduit 7 is arranged to pump liquid from the container 18 to and through the cylinder 1.

In the normal operation for liquid measuring, liquid is constantly supplied by pump 19 to the inlet conduits 3 and 5. In a starting condition, the inlet valve 9 is kept open and the inlet valve 11 is kept closed by means of the control unit 17. Simultaneously the outlet valve 12 is kept open and the outlet valve 10 is kept closed. By the pressure from the liquid entering the cylinder, the piston 2 will then move downwards, as seen in FIG. 1, so that liquid situated below the piston is forced out through the conduit 6 and further through the conduit 8. When the piston 2 reaches its lower position, this is sensed in a conventional manner, as by mechanical,

electrical or magnetic means (not shown), a signal being transferred to the control unit 17 so that it acts to close the valves 9 and 12 and open the valves 10 and I]. By the pressure from the liquid below the piston 2, the latter will now move upwards in the cylinder, liquid being forced out through the conduit 4 and further through the conduit 8. In a corresponding manner, upon sensing of the piston reaching its upper end position, the valves l and 11 will be reclosed, after which the valves 9 and 12 will be opened. The piston 2 in this manner moves to and fro within the cylinder 1, and liquid is dosed out through the conduit 8.

In FIG. 2, the cylinder 1 and the piston 2 are shown in detail. Parts of the inlet conduits 3, and outlet conduits 4, 6 are also shown in this figure.

As shown in FIG. 2, the cylinder 1 in the areas for the two end positions of the piston 2 has zones and 21 specially formed with somewhat larger inner diameter than the other part of the cylinder. These zones or recesses 20 and 21 communicate with the inlet and outlet at the respective ends of the cylinder. The piston 2 has special grooves 22 and 23 at its ends which receive annular seals 24 and 25, respectively. Further, the piston 2 has evenly distributed around its periphery, as can be seen from FIG. 3, three recesses 26, one of which is shown also in FIG. 2. The recesses 26 are situated between the seals 24 and 25. As can be seen from FIG. 2, the piston recesses 26 and each of the cylinder recesses 20 and 21 have an axial extension such that the piston recesses 26 will come into communication with the different cylinder recesses 20 and 21 in the respective end positions of the piston. In case the cylinder is placed so that its axis forms an angle with the horizontal plane, the piston recesses 26 serve to prevent gases from accumulating in the lower part of the cylinder. Thus, when the piston 2 is in its lower end position in FIG. 2, any gas bubbles present in the liquid below the piston will be collected in the piston recesses 26, wherein they accompany the piston 2 to its upper end position where they leave the recessed 26, which are then in communication with the outlet conduit 4 through the cylinder recess 20.

Due to the cylinder recesses 20 and 21, the piston seals 24 and will be uncovered alternately in the respective end positions of the piston 2, but there will always be one seal in sealing engagement with the inside of the cylinder 1. With this arrangement, it is possible to obtain an effective cleaning of the seals 24 and 25 and their grooves 22 and 23.

On cleaning, the valves 9-12 may be controlled in the same way as when the apparatus is in normal operation, the piston 2 then being reciprocated by the pressure of cleaning liquid supplied to the cylinder. By means of the control unit 17, however, the opening and closing movements of the valves may instead be controlled so that the piston will remain first in one and then in the other of its end positions, while cleaning liquid flows through the part of the cylinder where the piston is situated at the moment. Thus, when the piston is in the upper end position shown in FIG. 2, the valves ll and 12 are kept closed so that the liquid trapped in the lower part of the cylinder prevents the piston from moving downwards, while the valves 9 and 10 are kept open so that cleaning liquid flows through the part of the cylinder situated above the piston. The uncovered piston seal 24 and its groove 22 will then be effectively rinsed. In a corresponding manner, the valves 9 and 10 are kept closed while the valves 11 and 12 are kept open when the piston is situated in the lower end position, whereby the other piston seal 25 and its groove 23 will be effectively rinsed.

If required, these two cleaning methods may be combined. The cleansing of the piston seals and their grooves may be especially effective if the inlet conduits 3 and 5 open tangentially into the cylinder 1.

I claim:

1. Apparatus comprising a cylinder, a piston adapted to reciprocate in the cylinder between two end positions and having an annular seal at each end of the piston, whereby said seals are interposed between interior portions of the cylinder on opposite sides of the piston, the cylinder having at least one opening on each side of the piston, said openings serving as inlet and outlet for liquid, and means for controlling the flow of liquid into and out of the cylinder through said openings, the inside of the cylinder having at each end position of the piston an annular zone in which the internal diameter of the cylinder along a substantial part of its periphery is larger than the outer diameter of said annular seals, said zones communicating with respective cylinder openings and being located so that when the piston is in each end position, the piston seal nearest the corresponding cylinder end is opposite the corresponding zone while the other piston seal is in sealing engagement with the inside of the cylinder.

2. The apparatus of claim I, in which the cylinder has annular recesses forming said zones.

3. The apparatus of claim 2, in which said cylinder openings are located in the annular recesses.

4. The apparatus of claim 1, in which the axis of the cylinder forms an angle with the horizontal, the piston having at least one recess between its said seals, said recess and each of said cylinder zones having an axial extension such that the piston recess comes into communication with said zones as the piston arrives at its respective end positions.

5. The apparatus of claim 4, in which the piston has a plurality of said recesses extending in the axial direction of the cylinder and distributed evenly around the pistons periphery.

6. The apparatus of claim I, in which said cylinder openings include a separate inlet and a separate outlet on each side of the piston, said means including a valve in each of said inlets and outlets and being operable, when the piston is in either end position, to maintain the inlet and outlet open on the side of the piston adjacent said end position while maintaining the inlet and outlet on the other side of the piston closed.

7. The apparatus of claim 1, in which said means are valve means.

* i a I 

1. Apparatus comprising a cylinder, a piston adapted to reciprocate in the cylinder between two end positions and having an annular seal at each end of the piston, whereby said seals are interposed between interior portions of the cylinder on opposite sides of the piston, the cylinder having at least one opening on each side of the piston, said openings serving as inlet and outlet for liquid, and means for controlling the flow of liquid into and out of the cylinder through said openings, the inside of the cylinder having at each end position of the piston an annular zone in which the internal diameter of the cylinder along a substantial part of its periphery is larger than the outer diameter of said annular seals, said zones communicating with respective cylinder openings and being located so that when the piston is in each end position, the piston seal nearest the corresponding cylinder end is opposite the corresponding zone while the other piston seal is in sealing engagement with the inside of the cylinder.
 2. The apparatus of claim 1, in which the cylinder has annular recesses forming said zones.
 3. The apparatus of claim 2, in which said cylinder openings are located in the annular recesses.
 4. The apparatus of claim 1, in which the axis of the cylinder forms an angle with the horizontal, the piston having at least one recess between its said seals, said recess and each of said cylinder zones having an axial extension such that the piston recess comes into communication with said zones as the piston arrives at its respective end positions.
 5. The apparatus of claim 4, in which the piston has a plurality of said recesses extending in the axial direction of the cylinder and distributed evenly around the piston''s periphery.
 6. The apparatus of claim 1, in which said cylinder openings include a separate inlet and a separate outlet on each side of the piston, said means including a valve in each of said inlets and outlets and being operable, when the piston is in either end position, to maintain the inlet and outlet open on the side of the piston adjacent said end position while maintaining the inlet and outlet on the other side of the piston closed.
 7. The apparatus of claim 1, in which said means are valve means. 